Chill iron alloy castings



' CHILL moN ALLOY CASTINGS Paul W. Moss and George W. Moss, Saginaw,Mich., as-

signors to Eaton Manufacturing Company, Cleveland, Ohio, a corporationof Ghio No Drawing. Application December 7, 1954, Serial No. 473,742

4 Claims. (Cl. 14831) This invention relates to castings and moreparticularly to chill cast iron alloy castings, having a part of thecasting, adapted for Wear, made of chilled iron.

Broadly the invention comprehends the production of cast articles formedby casting specific iron alloy analysis compositions against'chillplates to form castings having extreme hardness and abrasive wearresistant surfaces in the white chilled portion thereof and gray ironadjacent the chilled portion.

Internal combustion engine valve tappets and like articles havingsurfaces thereof subject to abrasive wear have been devised and usedcommercially over a great period of time but have not been of a metalliccomposition as chilled at the wear surfaces to provide all that might bedesired so as to render said articles practically service free or afforda long life therefor. The invention as herein set forth makes use of aspecific iron alloy analysis such that in the use thereof in producing achilled white iron casting provides a very hard chilled surface havinghigh abrasive wear resistance and which will not spall or fatigue inpresent day engines in conjunction with present day detergent oils usedtherein. It is thus the basic object of this invention to provide anarticle of specific iron alloy analysis at least a portion of which iscast against a chill plate to produce a reasonably inexpensive articlecapable of having its chilled surface withstand abrasive wear.

The presently devised chilled iron alloy casting is intended primarilyfor engine valve tappet structures wherein one end or head surfacethereof is subject to abrasive wear by reason of engagement of theengine cam against said surface in the actuation of said tappet againstspring pressure imposed upon said tappet. In so utilizing an iron alloyof specific analysis together with the chill casting of at least aportion of a specific article therefrom, an article having a chilledsurface of very good wear characteristics is achieved. It is conceivablethat such an article could take any of various shapes aside from tappetsif like surfaces are des'ired subject to impact or heavy pressure.

The composition so utilized in carrying out this invention, that of achilled casting of iron, is characterized by its strength, hardness andtoughness, properties desired in parts subject to wear and containingthe following:

Percent Silicon 2.40-3.05 Manganese .70-1.10 Carbon 3.20-3.65 Molybdenum.50-1.00 Chromium .20-1.00 Nickel 1.20-2.00

Phosphorus and sulphur may be present within the ranges usually found incast iron.

For use in the production of engine valve tappets having a head thesurface of which is subjected to abrasive States Patent F Patented Aug.27, 1957 wear, good resultshave been obtained with a compositioncontaining approximately the following:

I Percent Silicon 2.70 Manganese .80 Carbon 3.50 Molybdenum .60 Chromium.70 Nickel 1.60

Impurities of phosphorus and sulphur Phosphorus and sulphur may bepresent within the ranges usually found in cast iron.

Such a composition, if chill cast, will produce a white iron having aRockwell C hardness 55 minimum as compared With ordinary chilled iron.

The present iron alloy composition is not only extremely hard andabrasive wear resistant in the chilled condition but it is strong andtough both in the chilled condition and gray iron condition. Thus thiscomposition is characteristically suitable for chilled castingssubjected to heavy pressure or impact, since such castings are lessliable to breakage than ordinary chilled iron castings.

In the production of tappet castings according to this invention theiron is first melted in an electric arc furnace and the chill depthadjusted to suit the purpose. Chill depth control is effected by varyingthe amount of chromium added and by the addition of graphitizers such ascarbon and silicon. After melting the iron it is poured into appropriateshaped molds, preferably green sand molds at a temperature in excess ofabout 2500 F. The sand molds as such prior to the pouring of the molteniron thereinto are supported upon chill plates to effect the desiredlocal chilling on the head surface of the tappets. Although green sandmolds are preferred it is conceivable that dry sand molds as well asshell molds could likewise be used. Subsequent to the casting of therough tappets they are machined and ground as required to finish sizeand condition ready for engine installation.

While this invention has been directed primarily to the production ofchilled iron alloy castings for use as engine tappets, it is readilyconceivable of use of said castings in the production of articles to besubjected to like impact and heavy pressure use in or out of contactwith presently developed and used detergent oils and ac- V cordingly,the appended claims are so directed basically to chilled iron alloycastings of specific metallic analysis.

What we claim is: v

1. A chilled casting, a portion of which is of chilled White iron andthe remainder of which is gray iron, containing silicon 2.40 to 3.05%,manganese .70 to 1.10%, carbon 3.20 to 3.65%, molybdenum .50 to 1.00%,chromium .20 to 1.00%, nickel 1.20 to 2.00% and the balancesubstantially all iron.

2. A chilled casting according to claim 1 wherein the casting is in theform of an engine tappet, the head of which is subject to detergent oilsunder impact and heavy loading in operational use, said head being thechilled white iron portion of the casting.

3. A cast engine tappet comprising a body portion and a head portion,said tappet containing by percent, silicon 2.40 to 3.05, manganese .70to 1.10, carbon 3.20 to 3.65, molybdenum .50 to 1.00, chromium .20 to1.00, nickel 1.20 to 2.00 and the balance substantially all iron, saidhead portion being of chilled white iron and said body portion being ofgray iron, whereby said head is highly resistant to corrosive fatiguing.

' 3 4 4. A cast engine tappet comprising a body portion References Citedin the file of this patent and a head portion, said tappet consistingsubstantially of UNITED STATES PATENTS 3.50% carbon, .80% manganese,2.70% silicon, 1.60% nickel, .70% chromium, .60% molybdenum and the hellZ; l i 5 yet ug. 0, 9 balance substantially all 1IO11, said head portionbeing of chilled White iron and said body portion being of gray OTHERREFERENCES iron, whereby said head is highly resistant to corrosiveAlloy Cast Iron Handbook, 2nd edition, pages 262-263.

fatiguing. Published in 1944 by the American Foundrymens Assn.

1. A CHILLED CASTING, A PORTION OFWHICH IS OF CHILLED WHITE IRON AND THEREMAINDER OF WHICH IS GRAY IRON, CONTAINING SILICON 2.40 TO 3.05%,MANGANESE .70 TO 1.10%, CARBON 3.20 TO 3.65%. MOLYDBENUM .50 TO 1.00%,CHROMIUM .20 TO 1.00%, NICKEL 1.20 TO 2.00% AND THE BALANCESUBSTANTIALLY ALL IRON.